[lammps-users] to set the specific region

Recently, I have started to use the LAMMPS program to apply to the deposition process for GaN system. At the first time, in order to make GaNsubstrate (Wurtize structure), I made the read_data file. To make the substrate, periodic boundary condition is usually applied in both x and y directions and the position of the bottommost two layers are fiixed. On the other hand, the atomic position of the other remaining layers is varied corresponding to the temperaure that I wish.

I don’t know how to set the specific region, such as fixed region, clamp region, and open surface region. Actually, I couldn’t use the ‘region’ command in LAMMPS program. When I used the ‘region’ command, I could observe the error message - ‘Use of region with undefined lattice’.

How can I solve this problem? Could you comment for me about this problem? I’ll wait for your reply e-mail.

Soon-Gun Lee

Dear Soon-Gun,
For region command to work without lattice, you need to put “units box” keyword in the command. However, it may or may not make sense towards your system. If you have read the data from data file and your box dimensions are actual distances in Angstroms, you should be fine with using keyword units box in the region command. Please correct me if I am wrong.


Vikas's answer is correct. What LAMMPS commands are you
wanting to use that require a region be specified?